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Biomedical subjects

D D Marciniuk

Publications and source records attributed to D D Marciniuk.

15 recordsLinked to original sources
PubMed2000

Role of respiratory function in exercise limitation in chronic heart failure.

OBJECTIVE: To test the hypothesis that respiratory function contributes to limit maximal exercise performance in patients with chronic heart failure by using the technique of dead space loading during exercise. DESIGN: Blinded subjects underwent two maximal incremental exercise tests in random order on an upright bicycle ergometer: one with and one without added dead space. SETTING: : Tertiary-care university teaching hospital. SUBJECTS: Seven patients with stable chronic heart failure (mean +/- SEM left ventricular ejection fraction, 27 +/- 3%). RESULTS: Subjects were able to significantly increase their peak minute ventilation during exercise with added dead space when compared with control exercise (57.4 +/- 5.9 vs 50.0 +/- 5.6 L/min; p < 0.05). Peak oxygen uptake, workload, heart rate, and exercise duration were not significantly different between the added dead space and control tests. Breathing pattern was significantly deeper and slower at matched levels of ventilation during exercise with added dead space. CONCLUSION: Because patients with chronic heart failure had significant ventilatory reserve at the end of exercise and were able to further increase their maximal minute ventilation, we conclude that respiratory function does not contribute to limitation of exercise in patients with chronic heart failure.

Adult↗
PubMed1999

Tolerance to the bronchoprotective effect of beta2-agonists: comparison of the enantiomers of salbutamol with racemic salbutamol and placebo.

BACKGROUND: Regular use of racemic salbutamol results in the partial loss of its bronchoprotective effect. The 2 enantiomers of salbutamol, the bronchodilator R-salbutamol and nonbronchodilator S-salbutamol, are now available. OBJECTIVE: We sought to compare the effect of regular use of S-salbutamol, R-salbutamol, racemic salbutamol, and placebo on the bronchoprotective effect of a single dose of racemic salbutamol against methacholine-induced bronchoconstriction. METHODS: Eleven of 13 well-controlled beta2 -agonist-free asthmatic subjects completed a double-blind, randomized study comparing racemic salbutamol 2.5 mg, S-salbutamol 1. 25 mg, R-salbutamol 1.25 mg, and diluent placebo nebulized and inhaled 3 times daily for 6 days (>/=6-day washout period). Ten to 12 hours after the last dose, the subjects performed measurement of FEV1, methacholine PC20, and a repeat methacholine PC20 done 1 hour after the first methacholine test and 10 minutes after 2 puffs (200 microgram) of racemic salbutamol administered from a metered-dose inhaler. The primary endpoint was the methacholine PC20 dose shift (Deltalog PC20/log 2) from before to after administration of 200 microgram of racemic salbutamol. RESULTS: The methacholine dose shift was 3.2 doubling doses (9-fold increase in methacholine PC20 after 200 microgram of racemic salbutamol) during the placebo treatment and was unaltered (3.2) after administration of S-salbutamol. The dose shift was significantly lower after both the R-salbutamol and racemic salbutamol treatments (2.2 and 2.6 doubling doses, respectively); there was no significant difference between R-salbutamol and racemic salbutamol. There was no treatment effect on baseline FEV1, baseline methacholine PC20, or bronchodilation. CONCLUSION: Regular treatment with racemic salbutamol or R-salbutamol, but not S-salbutamol, results in a partial loss of bronchoprotection, without loss of bronchodilation, compared with placebo.

Adrenergic beta-Agonists↗
PubMed1999

Detection of pulmonary tuberculosis in patients with a normal chest radiograph.

OBJECTIVES: To describe the early symptoms of pulmonary tuberculosis (TB) when the chest radiograph (CXR) is normal. SETTING: Centralized, provincial TB control program. SUBJECTS: Twenty-five patients with culture-positive pulmonary TB and a normal CXR were identified from a review of 518 consecutive patients with culture-positive pulmonary TB in the province of Saskatchewan from January 1, 1988 to March 31, 1997. Patients with abnormal CXRs at the time of diagnosis were excluded from the analysis. RESULTS: Twenty-three of the 25 patients (92%) were symptomatic at the time of diagnosis, with cough/sputum (76%) being reported most commonly. Eleven patients were identified because of contact tracing from cases of infectious pulmonary TB, while the other 14 patients were identified because of an investigation of symptoms. Twenty-four patients (96%) exhibited one or more symptoms of cough for > 1 month, fever for > 1 week, or skin-test conversion after contact with infectious TB. The sputum smear of only one patient was positive. Two patients were pregnant at the time of diagnosis, one patient was HIV-positive, and one patient demonstrated isoniazid-resistant organisms on sensitivity testing. Five patients were diagnosed as having primary TB associated with Mantoux skin-test conversion. The incidence of culture-positive pulmonary TB with a normal chest radiograph was < 1% in the period from 1988 to 1989 and steadily increased to 10% in the period from 1996 to 1997. CONCLUSIONS: Culture-positive pulmonary TB with a normal CXR is not uncommon, and the incidence of this presentation is increasing. Patients with this presentation of TB are typically symptomatic and/or are detected by contact tracing to infectious cases of pulmonary TB. The results suggest that patients presenting with a cough for > 1 month, with a fever for > 1 week, or with documented skin-test conversion < 2 years after known exposure to infectious TB should have sputum submitted for a Mycobacterium tuberculosis smear and culture despite a normal CXR.

Adolescent↗
PubMed1997

The current dilemma with spirometric inclusion criteria for asthma drug trials.

BACKGROUND: Spirometric inclusion criteria for asthma drug studies often require resting airflow obstruction and resting bronchoconstriction. By current standards, these criteria define suboptimal to poor asthma control. OBJECTIVE: To determine what proportion of asthmatic patients attending a tertiary University-based respiratory clinic meet typical drug study spirometric criteria of a baseline FEV1 of 50% to 80% predicted and > or = 15% delta FEV1 improvement following 200 micrograms inhaled albuterol. METHODS: A retrospective review was performed on charts of white caucasian asthmatic patients attending three respiratory physician outpatient clinics at a University-based tertiary referral center. We reviewed charts of all patients with chronic asthma under current therapy. We excluded subjects with additional lung diseases that might affect lung function. Spirometric data were extracted from the most recent scheduled outpatient visit. RESULTS: We reviewed 590 charts of patients with mean age 35.3 +/- 18.3 years (range 6 to 94), 43% male, and 50% atopic. There was objective evidence of variable airflow obstruction or airway hyperresponsiveness in 70.2%; the diagnosis of asthma was based on historical data alone in 29.8%. The majority of patients (87.5%) required inhaled corticosteroids with more than 50% using medium to high doses. Baseline FEV1 was > 80% in 84.6% of subjects, 50% to 80% in 14.4%, and < 50% in 1.0%. FEV1 improved by > or = 15% 10 to 15 minutes after 200 micrograms inhaled albuterol in 13.6%. Only 9.0% of the 590 asthmatic patients fulfilled both criteria (FEV1 50% to 80% and delta FEV1 > or = 15%). CONCLUSION: Less than 10% of asthmatic patients attending a tertiary referral respiratory clinic fulfilled typical spirometry inclusion criteria for asthma drug trials. We suggest this approach to enrollment in asthma drug studies be reevaluated.

Administration, Inhalation↗
PubMed1996

Clinical exercise testing in chronic airflow limitation.

Exercise testing has become an essential tool in the management of patients with CAL. In addition to its ability to assess exercise limitation objectively, it has usefulness in detecting the presence or absence of associated disease processes, in assessing the response to therapies, in allowing assessment of the importance of psychological factors in exercise limitation, and in guiding prescription for exercise rehabilitation programs. Although much is known about the clinical usefulness of exercise testing in this disease, and much has been learned about how this disease functionally impairs the exercise capacity of the patient, additional study is necessary to appreciate fully the physiologic abnormalities demonstrated by patients with CAL during exercise.

Cardiac Output↗
PubMed1996

Role of hypoxemia and pulmonary mechanics in exercise limitation in interstitial lung disease.

We have previously shown that respiratory factors (arterial hypoxemia and/or pulmonary mechanics) contribute to limit maximal incremental exercise in interstitial lung disease (ILD). In this study, we tested the hypothesis that arterial hypoxemia, not pulmonary mechanics, primarily limits maximal exercise in subjects with ILD. Seven subjects with ILD underwent two incremental exercise tests in random order. Test 1: breathing room air (RA); Test 2: breathing 60% O2 with added external dead space (O2VD). Added VD was used to prevent the fall in minute ventilation (VI) while breathing O2. All subjects demonstrated impaired exercise performance (maximal oxygen uptake [VO2], 56 +/- 13% predicted) while breathing RA. There was a significant increase in peak VI (RA, 64.9 +/- 22.3 L/min versus O2VD, 71.0 +/- 20.6; p < 0.05), maximal work rate (RA, 99 +/- 12 watts versus O2VD, 109 +/- 15 watts; p < 0.01), exercise duration (RA, 383 +/- 67 s versus O2VD; 426 +/- 72 s; p < 0.0005) and maximal VO2 (RA, 1.25 +/- 0.21 L/min versus O2VD, 1.39 +/- 0.26; p < 0.05) during the O2VD exercise test. There was a significant correlation between the percent increase in exercise duration during the O2VD test and the DLCO (r = -0.813, p < 0.05). At matched levels of ventilation, subjects demonstrated a significantly deeper and slower pattern of breathing during the O2VD test. Because subjects with ILD were able to further improve their exercise and further increase their VI during the O2VD exercise study, we conclude that arterial hypoxemia, and not respiratory mechanics, predominantly limits maximal incremental exercise in subjects with ILD.

Exercise Test↗
PubMed1995

Low-dose nebulized morphine does not improve exercise in interstitial lung disease.

Recent reports have suggested that low-dose nebulized morphine may improve exercise tolerance in patients with interstitial lung disease (ILD) by acting on peripheral opioid-sensitive pulmonary receptors. We therefore examined whether the administration of low-dose nebulized morphine would influence dyspnea or the breathing pattern during exercise of subjects with ILD and improve their exercise performance. Each of six subjects with ILD underwent three maximal incremental cycle ergometer tests, each test separated from the last by at least 3 d. Each exercise test was similar except that 30 min before exercise, the subjects received nebulized saline (control), morphine 2.5 mg, or morphine 5.0 mg, respectively, in double-blinded fashion. No significant differences were noted in exercise duration, maximal workload, or sense of dyspnea at the end of exercise in the control test and the tests with either morphine 2.5 mg or morphine 5.0 mg. Nor were significant differences noted in resting, submaximal, or end-exercise measurements of oxygen uptake (VO2), carbon dioxide output (VCO2), end-tidal CO2 (PETCO2), oxygen saturation (SaO2), minute ventilation (VI), respiratory frequency (f), tidal volume (VT), or heart rate (HR) in the three tests. Low-dose nebulized morphine did not alter the subjects' breathing pattern or affect the relationship between dyspnea and ventilation during exercise. No significant side effects were noted. The administration of low-dose nebulized morphine to subjects with ILD neither relieves their dyspnea during exercise nor improves their maximal exercise performance.

Double-Blind Method↗
PubMed1994

Lung volumes and expiratory flow limitation during exercise in interstitial lung disease.

Lung volumes were measured at rest and during exercise by an open-circuit N2-washout technique in patients with interstitial lung disease (ILD). Exercise tidal flow-volume (F-V) curves were also compared with maximal F-V curves to investigate whether these patients demonstrated flow limitation. Seven patients underwent 4 min of constant work rate bicycle ergometer exercise at 40, 70, and 90% of their previously determined maximal work rates. End-expiratory lung volume and total lung capacity were measured at rest and near the end of each period of exercise. There was no significant change in end-expiratory lung volume or total lung capacity when resting measurements were compared with measurements at 40, 70, and 90% work rates. During exercise, expiratory flow limitation was evident in four patients who reported stopping exercise because of dyspnea. In the remaining patients who discontinued exercise because of leg fatigue, no flow limitation was evident. In all patients, the mean ratio of maximal minute ventilation to maximal ventilatory capacity (calculated from maximal F-V curves) was 67%. We conclude that lung volumes during exercise do not significantly differ from those at rest in this population and that patients with ILD may demonstrate expiratory flow limitation during exercise. Furthermore, because most patients with ILD are not breathing near their maximal ventilatory capacity at the end of exercise, we suggest that respiratory mechanics are not the primary cause of their exercise limitation.

Airway Obstruction↗
PubMed1994

Oxygen improves maximal exercise performance in interstitial lung disease.

We examined whether arterial hypoxemia impairs incremental exercise performance in subjects with interstitial lung disease (ILD). Seven subjects underwent two incremental exercise tests on a bicycle ergometer in random order; one while breathing room air (RA), and the other while breathing 60% O2. Maximal exercise performance was impaired in all subjects: maximal oxygen uptake (peak VO2) was 56 +/- 4% predicted (+/- SEM); and all subjects demonstrated significant arterial oxygen desaturation during exercise breathing RA (mean 11 +/- 1%). Breathing 60% O2 during exercise resulted in a significant increase in peak VO2 (RA: 1.32 +/- 0.05 L/min; O2: 1.58 +/- 0.08 L/min; p < 0.05), exercise duration (RA: 390 +/- 21 s; O2: 458 +/- 24 s; p < 0.01) and maximal work load (RA: 112 +/- 6 watts; O2: 129 +/- 6 watts; p < 0.005). There was no significant difference in maximal minute ventilation (VI) achieved at the end of both tests. At matched ventilation (90% peak VI from the RA test), respiratory frequency (f) was significantly higher (RA: 33 +/- 2 breaths/min; O2: 35 +/- 2 breaths/min; p < 0.05), and tidal volume (VT) significantly lower (RA: 1.72 +/- 0.15 L; O2: 1.64 +/- 0.12; p < 0.05) when subjects exercised breathing oxygen. We conclude that arterial hypoxemia significantly impairs incremental exercise performance in subjects with ILD, but that mechanisms other than arterial oxygen desaturation are responsible for the rapid, shallow breathing pattern these subjects adopt during exercise.

Adult↗
PubMed1994

Dead space loading and exercise limitation in patients with interstitial lung disease.

STUDY DESIGN: We tested the hypothesis that maximal exercise performance in subjects with interstitial lung disease (ILD) is limited by respiratory factors. Assuming this is so, ventilatory stimulation by added dead space (VD) should impair exercise capacity. METHODS: Six subjects with ILD each underwent three maximal incremental exercise studies on a bicycle ergometer; control 1, added VD, and control 2. During the VD study, external VD (500 ml) was added to the circuit, and results obtained were compared with the mean results from the control studies. RESULTS: Exercise duration (TLIM) was significantly less in the VD study when compared to the control study (369 +/- 50 vs 439 +/- 55, p < 0.05), as was work rate (102 +/- 13 vs 125 +/- 14 W, p < 0.05) and peak oxygen uptake per minute (VO2) (1.08 +/- 0.09 vs 1.43 +/- 0.14 L/min, p < 0.05). At end-exercise, the Borg scale was higher in the VD study when compared to the control study (6 +/- 1 vs 5 +/- 1, p < 0.05), while no significant difference in minute ventilation (VI) or oxygen desaturation was noted. When compared to the control study at matched times during exercise, the addition of VD resulted in a significant increase in VI while no significant change was noted in VO2, carbon dioxide output (VcO2), or heart rate (HR). CONCLUSION: The decrease observed in TLIM, work rate, and peak VO2 with added VD, associated with a lack of change in VI or oxygen desaturation at end-exercise, suggests that exercise limitation in ILD is primarily due to respiratory factors.

Adult↗
PubMed1994

Clinical exercise testing in interstitial lung disease.

Clinical exercise testing has become an essential tool used in the early diagnosis, in the monitoring of treatment effectiveness, and in the assessment of impairment owing to ILD. Despite the assorted causes, the responses to exercise demonstrated by these diseases are generally similar. Although much has been learned about how these diverse diseases functionally impair the exercise capacity of the patient, further study is required if we are to understand fully the various physiologic abnormalities manifested by patients with ILD during exercise.

Biomechanical Phenomena↗
PubMed1993

Reproducibility of incremental maximal cycle ergometer testing in patients with restrictive lung disease.

BACKGROUND: Exercise testing has become an important tool in the diagnosis and treatment of restrictive lung disease. The reproducibility of variables measured during exercise testing was examined in subjects with stable restrictive lung disease. METHODS: Six subjects, who had never previously undergone exercise testing, each underwent three maximal incremental exercise studies on a bicycle ergometer conducted during a 28 day period. RESULTS: Data collected at rest, before exercise, were not significantly different during the three study days. Comparison of results at the end of the exercise tests from the three studies also revealed no evidence of a significant learning effect. Reproducibility of exercise performance by subjects was assessed by the coefficient of variation. The mean within subject coefficient of variation at the end of the exercise tests was 5.6% for work rate, 7.9% for exercise duration, and 9.5% for dyspnoea. The mean within subject coefficient of variation obtained at the end of the exercise tests was 5.3% for oxygen uptake (VO2), 2.5% for oxygen saturation (SaO2), 4.0% for heart rate (HR), 5.5% for minute ventilation (VE), 5.8% for respiratory frequency (f), and 4.6% for tidal volume (VT). The mean within subject coefficient of variation at 40% and 70% of maximal work rates for VO2 was 5.7% and 5.6% respectively, for SaO2 1.3% and 1.5%, for HR 4.8% and 4.0%, for VE 6.3% and 6.6%, for f 10.1% and 7.8%, and for VT 6.0% and 4.5%. CONCLUSIONS: Variables measured during clinical exercise testing in subjects with restrictive lung disease are highly reproducible. No significant learning effect was found on repeated testing in subjects who had never previously undergone exercise testing.

Adult↗
PubMedDate not supplied

Asthma management in the emergency department.

OBJECTIVES: To evaluate various aspects of the management of adult patients who present to the emergency department with acute exacerbations of asthma and who are discharged from the emergency department without hospital admission. Further, to compare the results with accepted management guidelines for the emergency department treatment of asthma. DESIGN: A retrospective chart collection and review until each site contributed 50 patients to the survey. SETTING: Three tertiary care hospitals in the Saskatoon Health District, Saskatoon, Saskatchewan. The study period was from July 1, 1997 to November 18, 1997. POPULATION: Patients aged 17 years or older, who were discharged from the emergency department with the diagnosis of asthma. METHODS: Data were collected on 130 patients from 147 emergency department visits. RESULTS: A number of important physical examination findings were frequently not documented. In contrast to management guidelines, peak expiratory flow rates (44%) and spirometry (1%) were not commonly used in patient assessments. Only 59% of patients received treatment in the emergency departments with inhaled or systemic corticosteroids. Furthermore, specific follow-up plans were infrequently documented in the emergency department charts (37%). CONCLUSIONS: Adherence with published Canadian guidelines for the emergency department management of acute asthma exacerbations was suboptimal. Corticosteroid use in the emergency department was significantly less than recommended. Increased emphasis on education and implementation of accepted asthma management guidelines is necessary.

Administration, Inhalation↗
PubMedDate not supplied

Tuberculosis in aboriginal Canadians.

Endemic tuberculosis (TB) was almost certainly present in Canadian aboriginal people (aboriginal Canadians denotes status Indians, Inuit, nonstatus Indians and metis as reported by Statistics Canada) before the Old World traders arrived. However, the social changes that resulted from contact with these traders created the conditions that converted endemic TB into epidemic TB. The incidence of TB varied inversely with the time interval from this cultural collision, which began on the east coast in the 16th century and ended in the Northern Territories in the 20th century. This relatively recent epidemic explains why the disease is more frequent in aboriginal children than in Canadian-born nonaboriginal people. Treatment plans must account for the socioeconomic conditions and cultural characteristics of the aboriginal people, especially healing models and language. Prevention includes bacillus Calmette-Guerin vaccination and chemoprophylaxis, and must account for community conditions, such as rates of suicide, which have exceeded the rate of TB. The control of TB requires a centralized program with specifically directed funding. It must include a program that works in partnership with aboriginal communities.

Antitubercular Agents↗